Pyrene aqueous solution

Other solubilization and partitioning phenomena are important, both within the context of microemulsions and in the absence of added immiscible solvent. In regular micellar solutions, micelles promote the solubility of many compounds otherwise insoluble in water. The amount of chemical component solubilized in a micellar solution will, typically, be much smaller than can be accommodated in microemulsion fonnation, such as when only a few molecules per micelle are solubilized. Such limited solubilization is nevertheless quite useful. The incoriDoration of minor quantities of pyrene and related optical probes into micelles are a key to the use of fluorescence depolarization in quantifying micellar aggregation numbers and micellar microviscosities [48]. Micellar solubilization makes it possible to measure acid-base or electrochemical properties of compounds otherwise insoluble in aqueous solution. Micellar solubilization facilitates micellar catalysis (see section C2.3.10) and emulsion polymerization (see section C2.3.12). On the other hand, there are untoward effects of micellar solubilization in practical applications of surfactants. Wlren one has a multiphase... 

Similar data were reported by Turro et al., [62,63] who synthesized a copolymer of AA with 1.5 mol% of 2-[4-(l-pyrene)butanoyl]aminopropenoic acid, 19 and studied the fluorescence quenching with Tl +, Cu2+, and 1 ions in aqueous solution. 

Samples for studies of CDx effects on fluorescence enhancement in organic solution were prepared using pyrene, because pyrene possesses a long lifetime and is very susceptible to quenching and enhancement in solution (23). An aliquot of pyrene stock solution in cyclohexane was placed under a nitrogen purge to evaporate the cyclohexane. Samples were redissolved in a 1 A mixture of Isopropyl ether and 1-butanol, which was saturated with aqueous CDx solution. Pyrene samples were also prepared in which the organic solvent was not saturated with CDx solution. The mixed solvent was used in order to minimize the effects of ether evaporation and thus allow more accurate quantitation. Fluorescence measurements were made on diluted samples of these solutions. The solvent used to make up the... 

FIGURE 5.24 Release of aminomethyl-pyrene from dendron 31 upon removal of the Boc protecting group trigger (1 1 MeOH/DMSO mixture with 2% aqueous solution of Bu4NOH) ( ) Control reaction under similar conditions with dendron 31 with the Boc trigger intact (A)-... 

Site I is characterized by a relatively large red shift of 10 nm in the absorption maxima (relative to the aqueous solution spectra), exhibiting maxima at 337 and 354 nm, and a negative AA spectrum all of these properties are consistent with an intercalation-complex geometry in which the planar pyrene ring-system is nearly parallel to the planes of the DNA bases. 

Cascade Blue cadaverine and Cascade Blue ethylenediamine both contain a carboxamide-linked diamine spacer off the 8-methoxy group of the pyrene trisulfonic acid backbone. The cadaverine version contains a 5-carbon spacer, while the ethylenediamine compound has only a 2-carbon arm. Both can be coupled to carboxylic acid-containing molecules using a carbodiimide reaction (Chapter 3, Section 1). Since Cascade Blue derivatives are water-soluble, the carbodiimide EDC can be used to couple these fluorophores to proteins and other carboxylate-containing molecules in aqueous solutions at a pH range of 4.5-7.5. The reaction forms amide bond linkages (Figure 9.39). 

Fig. 25 Semilogarithmic plots of the changes of ratio I1/I3 for pyrene in aqueous solutions of homopolymer PVCL and grafted copolymers at 20° C as a function of polymer concentration. Homopolymer PVCL (a), PVCL-g-6 (b), PVCL-g-13 (c), PVCL-g-16 (d), PVCL-g-18 (e), PVCL-g-34 (/). (Reprinted with permission from Ref. [180] copyright 2005 Elsevier)...

The most common linker molecules are pyrene derivatives, which have been used, for example, to link Au [64,65] and Pd [66] NPs, as well as QDs [67] to CNTs. Martin et al. chemically attached a n-extended tetrathiafulvalene (exTFF) group to pyrene prior to n-n hybridization on SWCNTs in order to investigate donor-acceptor interactions between the SWCNT and electron rich exTFF [68], More recently, the same group has synthesized a complex molecule consisting of two exTFF anchors connected via a flexible linkage that also consists of a second generation carboxylic terminated den-dron [69]. Here, n interactions between the exTFF anchors and the SWCNTs lead to hybridization while the carboxylic acid groups of the dendron (when de-protonated) lead to increased solubility in aqueous solutions [69]. 

Nitropyrene was the sole product formed from the gas-phase reaction of pyrene with OH radicals in a NOx atmosphere (Arey et al, 1986). Pyrene adsorbed on glass fiber filters reacted rapidly with N2O5 to form 1-nitropyrene. When pyrene was exposed to nitrogen dioxide, no reaction occurred. However, in the presence of nitric acid, nitrated compounds were produced (Yokley et al, 1985). Ozonation of water containing pyrene (10-200 pg/L) yielded short-chain aliphatic compounds as the major products (Corless et al, 1990). A monochlorinated pyrene was the major product formed during the chlorination of pyrene in aqueous solutions. At pH 4, the reported half-lives at chlorine concentrations of 0.6 and 10 mg/L were 8.8 and <0.2 h, respectively (Mori et al, 1991). 

A combined effect of natural organic matter and surfactants on the apparent solubility of polycyclic aromatic hydrocarbons (PAHs) is reported in the paper of Cho et al. (2002). Kinetic studies were conducted to compare solubilization of hydro-phobic contaminants such as naphthalene, phenanthrene, and pyrene into distilled water and aqueous solutions containing natural organic matter (NOM) and sodium dodecyl sulfate (SDS) surfactant. The results obtained after 72hr equilibration are reproduced in Fig. 8.19. The apparent solubility of the three contaminants was higher in SDS and NOM solutions than the solubility of these compounds in distilled water. When a combined SDS-NOM aqueous solution was used, the apparent solubility of naphthalene, phenanthrene, and pyrene was lower than in the NOM-aqueous solution. 

Zhang et al. [135] have studied the physicochemical behavior of mixtures of -dodecyl-/l-D-maltoside with anionic, cationic and nonionic surfactants in aqueous solutions. To acquire information on the property of mixed micelles, the characteristic change of pyrene with changes in polarity was monitored. The polarity parameter at low concentrations was found to be 0.5-0.6. 

Critical micelle concentration in aqueous solutions was determined by fluorescence using pyrene as a probe. The driving force for micelle formation is the strong hydro-phobic interactions between [(R)-3-hydroxybutyrate] block. It was previously determined by this group that terpolymers with longer PHB blocks have much lower critical micelle concentrations because of PHB block aggregation in aqueous solution. Testing results are provided in Table 2. 

The 0.1% polymer derivative contains about one molecule of pyrene per macromolecule, whereas the 5% one has 50 to 60. The distribution of ligand on the polymer is at best binominal.42 Thus a significant fraction of the former derivative contains two to five molecules of pyrene per macromolecule. It is surprising to find excimer formation in the 0.1% derivative since so few molecules are on a single polymer chain. It seems apparent, therefore, that in aqueous solution these moieties on the polymer are clustered in the ground state so that excimer formation is facilitated. 

As Fig. 15b illustrates, the graphical relation appears to be linear for an interaction number of 3 to 4, if A 1. Alternatively, for A = 1, linearity is evident (Fig. 15c) when the interaction number is 5 to 6. Thus a large value of A is compatible with the smallest interaction number. Excimer formation occurs within the fluorescence lifetime, about 8 nsec. Within that time the pyrene-labeled amine side chains must approach within about 4 A of each other. For the 5.3% pyrenylpolyethylenimine derivative in ethanol, where no ground-state association occurs, the effective local concentration of pyrene on the polymer matrix is about 10-2 M, as calculated from excimer fluorescence. In aqueous solution, where clusters form within the polymer matrix, the effective local concentration of pyrene adduct must be even greater. The quantitative assessment of fluorescence intensities (Fig. 15) points to a minimum interaction number of 3 to 4 pyrenyl-labeled amine side chains, within the 8 nsec lifetime. Since A 1, it appears from (12) that kDM(A) kMD + kD. Thus excimer formation must be very rapid in the polymer environment. We can conclude, therefore, that the primary-amine side chains of poly-ethylenimine are very flexible and mobile. 

In order to estimate how the bioavailability of benzo(a)pyrene (BP) is affected by DOM, you want to assess the speciation of this compound as a function of DOM quantity and quality. To this end, calculate the fw value of BP for aqueous solutions (pH 7, 25°C) containing (a) 10 mg DOC-L"1 and 100 mg DOC-L"1, respectively, and (b) assuming DOM qualities as reflected by the LFERs 1 and 7 in Fig. 9.16 (see figure caption for slopes and intercepts). Note that DOM 1 represents a humic acid that exhibits a high affinity for PAHs, whereas DOM 7 is a fulvic acid with a low affinity. Hence, the two DOMs may represent extreme cases with respect to sorption of apolar and weakly polar compounds in natural waters. 

Figure 11.6 Sorption isotherms for two kinds of nonionic organic compounds from aqueous solutions to suspended kaolinite (a) slightly monopolar compound, pyrene, showing a linear isotherm up to its solubility (Backhus, 1990), and (b) monopolar compound, 1,3,5-trinitrobenzene, showing a hyperbolic isotherm (Had-erlein et al., 1996).

Table II. Retention of Biphenyl, Phenanthrene, and Pyrene in Aqueous Solutions during Vacuum Distillation and Lyophilization...

Figure 3. Adsorption of solutes to silanized glass wool and silanized glass beads. Aqueous solutions of caffeine ( ), 15 mg/L ethidium bromide (O), 10 mg/L or pyrene ( ), 0.14 mg/L were passed through 5-mL beds of silanized glass wool (left) or silanized glass beads (right).

Fluorescence quenching in micelles. Consider an aqueous solution with a high concentration of micelles (Box 26-1) and relatively low concentrations of the fluorescent molecule pyrene and a quencher (cetylpyridinium chloride, designated Q), both of which dissolve in the micelles. 

Phenanthrene and pyrene on treatment with diisopropylcarbodiimide, hydrogen peroxide, and acetic acid in ethyl acetate at room temperature give 1 and 4 in 28% and 27% yields, respectively.17 Similar reaction occurs with dicyclohexylcarbodiimide and cyclohexylbenzylcarbodiimide. The hydrogen peroxide can be either 98% or a 30% aqueous solution. Use of silica gel, Dowex 50W-X8, or diphenylphosphinic acid instead of acetic acid is also permissible. However, because of the sensitivity of arene oxides toward strong acids, hydrochloric, sulfuric, or polyphosphoric acids cannot be used. 

The results obtained in AOP-treatment of pyrene in aqueous solutions were quite similar to those of anthracene and phenanthrene. For pyrene, ozonation has been more effective at lower pH values than at neutral pH values. The half-lives of pyrene at pH 3,7, and 9 are 17,24, and 42 s, respectively however, the half-life of pyrene increased in the series of 03 < UV/03 < 03/H20 < UV/ 03/H202 (Trapido et al., 1995). The UV degradation of pyrene is quite fast the half-life is only 69 s (Trapido and Veressinina, 1995). Figure 14.23 illustrates the oxidation kinetics of anthracene and pyrene in neutral media. 

The host properties are also impressively demonstrated by inclusion of pyrene in aqueous solution (Fig. 6.20b). It also proved possible to introduce the anti-inflam-... 

The (3-CD derivative bearing two pyrenes attached at one appending chain (75) was also prepared [72]. It exhibits both monomer and excimer emissions even though the excimer emission is remarkable in a 20% DMSO aqueous solution. This system is also responsive to guest compounds, and a remarkable decrease in the excimer emission was observed when lithocholic acid was added. 

Enhanced excimer emission was also observed from PBAC bound to a-ZrP [20], Excimer formation from pyrene is well known in aqueous solutions [54], As in the case with AMAC, excimer formation is increased with PBAC concentration (Fig. 16) due to increased local concentrations but with two significant differences. Hydrophobic interactions between the pyrene molecules favor the aggregation of PBAC even at moderate coverages and the PBAC singlet excited state is much longer lived ( 200 nsec) than that of AMAC ( 10 nsec) these factors, in turn, promote excimer formation even at low loadings. The broad, red-shifted fluorescence band with a peak centered around 470 nm, characteristic of the pyrene excimer emission, is evident in Fig. 16. Rapid formation of the excimer at low coverages is also evident from the plot of the ratio of emission intensities at... 

It is believed that two crowns bind a K+ ion, thus leading to loosely preassembled bis-pyrene subunits. When the metal ion recognition event occurs in the presence of y-CD, dramatic enhancements of excimer emission are observed, thus providing a method to selectively detect K+ ion in aqueous solution. This ability to sense an ionic analyte is unusual for CD chemosensors. Modification of 28 with other ion binding sites should provide a general method for cation detection. 

In this report we represent the results of Raman and NIR absorption spectroscopy of SWNT with organic molecules (pyrene and naphthalene) in a film and with various surfactants (cationic, anionic and nonionic) in aqueous solution. 

Noncovalent interaction of SWNTs with organic molecules (pyrene and naphthalene) and surfactants of different types in aqueous solutions leads to the spectral shift of lines and its intensity redistribution in spectra in comparison with the spectra of pristine SWNT. 

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